The invention is based on a fuel injection pump for internal combustion engines as defined hereinafter. The problem in such pumps is that for exact regulation, the association, or relationship, of the axial position of the control slide with respect to the axial location of the control opening in the jacket face of the pump piston must be exactly the same for all the pump elements. In other words, closing or opening of the control opening by the control slide must take place at exactly the same axial, or stroke, position of the pump piston with respect to the rotational position of the drive shaft, in terms of the base circle of the cam. Errors in tolerance arise during manufacture, first during machining and then during assembly, and such errors can then become compounded. Typically, these errors in tolerance are eliminated by aligning the control slides identically with respect to the control openings before the pump is put into operation.
In a known fuel injection pump of this generic type (German Offenlegungsschrift No. 35 22 414), the driver tang is secured to a fastening clip that encompasses the torque shaft, so that once the fastening clip is loosened, the driver tang and hence the axial position of the control slide relative to the rotational position of the torque shaft is variable. Aside from the fact that this adjusted relative position between the driver tang and the torque shaft undergoes intrinsic variations given the heavy load and severe vibrations typical of a fuel injection pump, the effort of adjustment is also relatively great, because a direct comparison between the individual pump elements must be made during the adjustment, and when the fastening clips are set on the torque shaft, torque is exerted upon it, which in turn can cause adjustment errors. Another disadvantage is that the adjustment can be performed only after installation, since otherwise the individual association of the change in rotational position between the torque shaft and the fastening clip to the change in the axial or stroke position of the control slide cannot be reliably performed; this has the disadvantage that for setting purposes, it is necessary to intervene in the suction chamber, which is under feed pump pressure.
In another fuel injection pump of this generic type (German Offenlegungsschrift No. 35 40 052), the driver tang is eccentrically disposed on a spindle that passes radially through the torque shaft and is clamped firmly to it with a tensioning nut. When this spindle rotates, which can be effected via a screwdriver slot and a screwdriver after the tensioning nut is loosened, the driver tang is adjusted with respect to the axial position of the control slide, in accordance with the eccentricity of the driver tang. Once again, in this known apparatus, self-loosening of the established setting is even more disadvantageous, the smaller the frictional surfaces involved in the tightening of the spindle. Furthermore, this adjustment can likewise be made only after the torque shaft has been installed, and once again the suction chamber, which is under pressure, has to be opened. In yet another known fuel injection pump of this generic type (European patent application No. 0181402), a fork-like device having a gripper insert is used as the driver element, being either in the form of a tubular clip joined to a round torque shaft, or being joined to a torque shaft of polygonal cross section via a bolt disposed on the face end of this fork lever that faces toward the torque shaft. In the first case, the adjustment is admittedly relatively simple, effected by rotating the "tubular clip" on the torque shaft. There is the danger, however, that because of the vibrational strain on such systems the clip tension may very easily loosen, causing shifting or misalignment of the control association, possibly in the direction of an increasing fuel quantity, which causes the engine to race. The other version [with the polygonal shaft] is extremely unfavorable in terms of force transmission, because the effective contact surface in the longitudinal direction of the lever between the lever part and the torque shaft is relatively narrow, and besides, there is no way to make an adjustment of the desired kind mentioned above.